diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ad10f58..a8b8400 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -7,14 +7,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: ["14", "15", "16", "17", "18"]
+        node: ["14", "15", "16", "17", "18" ]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: setup node
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node }}
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: node_modules
           key: customerio-${{ matrix.node }}-${{ hashFiles('package-lock.json') }}
diff --git a/lib/api.ts b/lib/api.ts
index 1c6e8bf..dd7408e 100644
--- a/lib/api.ts
+++ b/lib/api.ts
@@ -1,7 +1,7 @@
 import type { RequestOptions } from 'https';
 import Request, { BearerAuth, RequestData } from './request';
 import { Region, RegionUS } from './regions';
-import { SendEmailRequest, SendPushRequest } from './api/requests';
+import { SendEmailRequest, SendPushRequest, SendSMSRequest } from './api/requests';
 import { cleanEmail, isEmpty, isIdentifierType, MissingParamError } from './utils';
 import { Filter, IdentifierType } from './types';
 
@@ -85,6 +85,14 @@ export class APIClient {
     return this.request.post(`${this.apiRoot}/send/push`, req.message);
   }
 
+  sendSMS(req: SendSMSRequest) {
+    if (!(req instanceof SendSMSRequest)) {
+      throw new Error('"request" must be an instance of SendSMSRequest');
+    }
+
+    return this.request.post(`${this.apiRoot}/send/sms`, req.message);
+  }
+
   getCustomersByEmail(email: string) {
     if (typeof email !== 'string' || isEmpty(email)) {
       throw new Error('"email" must be a string');
@@ -160,4 +168,4 @@ export class APIClient {
   }
 }
 
-export { SendEmailRequest, SendPushRequest } from './api/requests';
+export { SendEmailRequest, SendPushRequest, SendSMSRequest } from './api/requests';
diff --git a/lib/api/requests.ts b/lib/api/requests.ts
index 9623e49..104390d 100644
--- a/lib/api/requests.ts
+++ b/lib/api/requests.ts
@@ -167,3 +167,40 @@ export class SendPushRequest {
     }
   }
 }
+
+export type SMSMessage = Partial<SendSMSRequestOptions>;
+
+export type SendSMSRequestRequiredOptions = {
+  identifiers: Identifiers;
+  transactional_message_id: string | number;
+};
+
+export type SendSMSRequestOptionalOptions = Partial<{
+  to: string;
+  disable_message_retention: boolean;
+  send_to_unsubscribed: boolean;
+  queue_draft: boolean;
+  message_data: Record<string, any>;
+  send_at: number;
+  language: string;
+}>;
+
+export type SendSMSRequestOptions = SendSMSRequestRequiredOptions & SendSMSRequestOptionalOptions & {};
+
+export class SendSMSRequest {
+  message: SMSMessage;
+
+  constructor(opts: SendSMSRequestOptions) {
+    this.message = {
+      identifiers: opts.identifiers,
+      to: opts.to,
+      transactional_message_id: opts.transactional_message_id,
+      disable_message_retention: opts.disable_message_retention,
+      send_to_unsubscribed: opts.send_to_unsubscribed,
+      queue_draft: opts.queue_draft,
+      message_data: opts.message_data,
+      send_at: opts.send_at,
+      language: opts.language,
+    };
+  }
+}
diff --git a/test/api.ts b/test/api.ts
index 787201d..63bfde3 100644
--- a/test/api.ts
+++ b/test/api.ts
@@ -6,6 +6,7 @@ import {
   DeliveryExportRequestOptions,
   SendEmailRequest,
   SendPushRequest,
+  SendSMSRequest,
 } from '../lib/api';
 import { RegionUS, RegionEU } from '../lib/regions';
 import { Filter, IdentifierType } from '../lib/types';
@@ -499,3 +500,68 @@ test('#getAttributes: success with type email', (t) => {
     ),
   );
 });
+
+test('sendSMS: passing in a plain object throws an error', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+
+  let req = { identifiers: { id: '2' }, transactional_message_id: 1 };
+
+  t.throws(() => t.context.client.sendSMS(req as any), {
+    message: /"request" must be an instance of SendSMSRequest/,
+  });
+  t.falsy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/sms`));
+});
+
+test('#sendSMS: with template: success', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+  let req = new SendSMSRequest({
+    to: '+1234567890',
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+  });
+  t.context.client.sendSMS(req);
+  t.truthy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/sms`, req.message));
+  t.is(req.message.transactional_message_id, 1);
+  t.is(req.message.to, '+1234567890');
+});
+
+test('#sendSMS: with optional parameters: success', (t) => {
+  sinon.stub(t.context.client.request, 'post');
+  let req = new SendSMSRequest({
+    to: '+1234567890',
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+    message_data: { key: 'value' },
+    disable_message_retention: true,
+    send_to_unsubscribed: true,
+    queue_draft: true,
+    send_at: 1234567890,
+    language: 'en',
+  });
+  t.context.client.sendSMS(req);
+  t.truthy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/sms`, req.message));
+  t.is(req.message.transactional_message_id, 1);
+  t.is(req.message.to, '+1234567890');
+  t.deepEqual(req.message.message_data, { key: 'value' });
+  t.true(req.message.disable_message_retention);
+  t.true(req.message.send_to_unsubscribed);
+  t.true(req.message.queue_draft);
+  t.is(req.message.send_at, 1234567890);
+  t.is(req.message.language, 'en');
+});
+
+test('#sendSMS: error', async (t) => {
+  sinon.stub(t.context.client.request, 'post').rejects({ message: 'sample error', statusCode: 400 });
+
+  let req = new SendSMSRequest({
+    to: '+1234567890',
+    identifiers: { id: '2' },
+    transactional_message_id: 1,
+  });
+  t.context.client.sendSMS(req).catch((err) => {
+    t.is(err.message, 'sample error');
+    t.is(err.statusCode, 400);
+  });
+
+  t.truthy((t.context.client.request.post as SinonStub).calledWith(`${RegionUS.apiUrl}/send/sms`, req.message));
+});